How much does it cost to insulate an attic?

Insulation is a material used to prevent heat loss or heat gain. It effectively creates a barrier between two spaces to control temperature variances. Homes contain insulation that is made from either spun glass (fiberglass 1) or rock substances that have been heated and spun into fine, hair-like material (rock wool) and a binding agent is used to hold these materials together. Some homes may also have insulation boards or spray foam as an insulate.

A properly insulated home and attic can save 10 to 50 percent off your home’s power bill, according to the U.S. Department of Energy. Heat rises in a home, and without attic insulation, it quickly escapes through the home’s roof. Insulation prevents heat and cooling loss in the home, so with attic insulation, your home will feel warmer in the winter and cooler in the summer.

An average-size attic of 1,200 square feet will usually cost about $1,700-$2,000 for blown-in cellulose or fiberglass.

Energy audit

Ideally, prior to insulating your attic, you should have an energy audit to determine where your home may be losing energy. Many energy companies offer this service. It will help you determine what type of insulation is best for your home. An energy audit will typically cost around $150.

Cost factors

When picking insulations, you will want to consider cost as well as ease of installation and how well the insulation will reach all the areas in your attic. d

Nowadays, blown-in cellulose or fiberglass 1 remain almost identical in price. However, prices are constantly changing. Fifteen years ago, fiberglass cost twice as much as cellulose. Rolled fiberglass or rock wool insulation, known as batt, is the least expensive form of insulation. Spray foam and foam board are the most expensive forms of insulation and are rarely used for attic space because of the higher cost.

Many things can cause the price of attic insulation installation to vary, such as the size of the overall attic, the amount of existing insulation, and the number of ventilation fans in the home’s roof. If there is existing insulation it will often need to be removed before applying new. Insulation will need to be installed around vent fan openings. Overall, the complexity of the project is a factor in the final cost.

How to know if your attic needs insulation

There are several indicators that you need insulation in your attic:

Ice dams: ice dams are heavy buildups of ice along the home’s eaves. They can damage a home’s shingles, wood, and overall roof. Ice dams develop when an attic is inadequately insulated and allows the hot air from the home’s interior to escape through the roof. The escaping hot air melts the snow which runs down the roof of the house and forms ice dams along the eaves.

Temperature variances: if the rooms in your house vary in temperature it may indicate areas of your attic that are not properly insulated.

Drafts: drafts in a room indicate poor attic insulation.

Expensive energy bills: if your energy bill is higher than other homes in your area that are comparable in size then you may have an attic insulation problem.

Insulation types

There are numerous types of insulation to consider when insulating your attic. You should talk to your insulation installation company to determine which type of insulation best fits your attic’s needs.

Usually has a much higher R-value (see below) than other insulation forms of the same thickness

Rigid foam cannot be used to insulate existing walls

Blanket batts and rolls

R-11: $0.12-$0.16 per sq.ft.

R-13: $0.15-$0.20 per sq.ft.

R-19: $0.27-$0.34 per sq.ft.

R-25: $0.37-$0.45 per sq.ft.

R-30: $0.39-$0.47 per sq.ft.

R-38: $0.55-$0.60 per sq.ft.

Easy to install

Fiberglass blankets and batts only have an R-value of R-2.9 to R-3.8 per inch of thickness

Need to add 10-12 inches of insulation to obtain enough insulation for an attic

Takes up a great deal of room

Certain types of insulation work best in various areas of your home. To determine which type of insulation you should use in your attic, you should talk with your attic insulation company.

Insulation Type

Best Places to Use

Blown-in

Attic because it can be blown into all areas of the attic - the floor, walls, roof, and around joists.

It is wonderful for a finished attic because it can be blown in under flooring and behind walls without needing to tear out any areas of the attic.

Blankets, batts, and rolls

Walls, floor, and roof of the attic.

Spray Foam

Attic’s walls, floor, and roof.

It is especially beneficial when used to fill in gaps around vent fans, skylights, and plumbing fixtures.

Foam Board

Walls.

It is rarely used on the floors or roof of the attic.

R-value

R-value explains the resistance to heat flow through a certain thickness of the material. The higher the R-value, the greater the heat flow resistance and the better the insulation. The thicker the insulation, the great the R-value. Many people mistakenly believe that doubling the insulation will provide a double R-value. However, insulation must be the correct thickness and installed properly to gain the greatest R-value.

Insulation type

R-value and thickness

Price

Batts or rolls

R-11, 3½-inch thick

R-13, 3⅝-inch thick

R-19, 6¼-inch thick

R-25, 8¼-inch thick

R-30, 9½-inch thick

R-38, 12-inch thick

R-11: $0.12-$0.16 per sq.ft.

R-13: $0.15-$0.20 per sq.ft.

R-19: $0.27-$0.34 per sq.ft.

R-25: $0.37-$0.45 per sq.ft.

R-30: $0.39-$0.47 per sq.ft.

R-38: $0.55-$0.60 per sq.ft.

Blown-in

R-20, 6 inches deep

R-31, 9 inches deep

R-42, 12 inches deep

R-20: $0.65-$0.80 per sq.ft.

R-31: $.85-$1.10 per sq.ft.

R-42: $1.25-$1.45 per sq.ft.

Foam board

R-3, ½-inch thick

R-7.5, 1½-inch thick

R-6, 1½-inch thick

R-16, 4-inch thick

½-inch thick: $0.28-$0.38 per sq.ft.

1-½-inch thick: $0.60-$0.80 per sq.ft.

Spray foam

R-22.4, 3½-inch thick

R-38.4, 6-inch thick

R-57.6, 9-inch thick

R-76.8, 12-inch thick

Open cell: $0.44-$0.65 per board foot

Closed cell: $0.70-$1.00 per board foot

Vapor barrier

Years ago it was recommended that a vapor barrier 3 be installed to keep water and air from penetrating the attic. However, current standards are to no longer use a vapor barrier that forms a barrier between the insulation and the drywall 4 of the ceiling because it can actually trap moisture and create mold growth.

Parts that need insulation

Many people mistakenly believe that simply laying or spraying insulation into an attic onto the floors and ceilings will suffice to insulate the space. However, there are other parts of an attic that require insulation. Most attics have pipes that run through them. Insulating warm water pipes in the attic will keep the water warmer and also conserve energy. All wiring inlets/outlets, chimney rim space, and exhaust fans will also require insulation with a material such as spray foam. The walls, floor, ceiling, and rafters will all need insulation. If there are any air leaks around windows, pipes, wires, fans ducts, light fixtures, flooring, or the chimney then they will need to be insulated. For such difficult areas, many insulation installers opt to use spray foam to fill in any leaks or gaps.

Storage decking

Attics that have adequate space are often used for storage. It is advised that you lay insulation on the attic floor and then lay storage decking over the surface expanse of the insulation. This provides a firm planking to store items while protecting the installed insulation.

Labor and installation process

Labor and installation should be done by a licensed contractor. Most licensed insulation companies charge about $0.95 per foot for labor. This price does not include materials.

There are numerous types of insulation that require different methods of installation:

Blown-in cellulose or fiberglass 1 can be installed with a machine that blows the fibers into place. A small amount of moisture is added to the installation prior to spraying so that it adheres to the surfaces of the attic.

The batts or rolls are usually stapled into place. They usually have a paper backing and the paper backing is placed so that it faces the heat source.

Spray foam must always be sprayed into an attic by a licensed and experienced contractor.

Finished vs unfinished attic

A finished attic is more difficult to insulate because there is usually flooring and sheetrock 4 in place. The insulation must be placed under the flooring and behind the sheetrock. One of the easiest methods is to use blown-in insulation between the walls and the ceiling. Using blown-in insulation requires less tear out and rebuild and will effectively reach the rafters and wall joists coating them in a covering of insulation.

Many older attics are under-insulated and require additional insulation. Remember that the greatest R-value is obtained by adding extra inches of insulation. R-value can be doubled just by adding extra insulation on top of existing insulation. Adding additional insulation only works if there is enough space to accommodate the extra insulation. However, some insulation companies will require that the old insulation be removed and a new, higher R-value insulation added.

Insulating and finishing an attic can easily turn the space into additional air-conditioned/heated living space. The insulation is laid in the floor space, wall spaces, and ceiling of the attic. The insulation is then covered with wood and sheetrock to create a finished living area. Heating and air conditioning ducts can also be run into the attic space to create a climate-controlled space.

Enhancements and improvement costs

Soundproofing

Soundproofing eliminates any noise from inside the house reaching the outside and also prevents outdoor noise from reaching the home’s interior. Usually, a 1,000 sq.ft. space costs $8,000-$12,000 to soundproof.

Mold remediation

Mold is an invasive fungus that can become a problem in your attic if moisture is present. Mold remediation services often need to be undertaken before an attic space can be insulated. Mold remediation usually costs from $2,000-$6,000.

Humidity repairs

In humid areas of the country, a dehumidifier often needs to be installed in an attic to reduce the humidity level. Having a dehumidifier installed usually costs $1,500-$2,500.

Additional considerations and costs

Rebates

There are usually numerous federal and state incentives and rebates when you opt to insulate your attic. Federal tax credits tend to be 10 percent of the final cost of the insulation process.

DIY

Rolls, boards, and batts can often be installed easily with a DIY process but blown-in and spray foam insulation require an experienced contractor.

Regulations

Depending on what state you live in, there are distinct insulation regulations. In some areas, the insulation must be installed with a second layer that lies at right angles to the first to increase the depth of the insulation.

Checking vents and exhaust fans

You should ensure that all vents and exhaust fans are directed to the exterior of the house.

FAQ

Which is the best attic insulation?

Cellulose or fiberglass 1 blown-in insulation is easy and less costly to have done than spray foam. It works well and easily reaches all corners of the attic. It can be applied in the walls of the attics, around the roof joists, and in many tight locations where batts and rolls cannot be easily fitted.

How much does it cost to put insulation in the attic?

An average-size attic of 1,200 square feet will usually cost about $1,700-$2,000 for blown-in cellulose or fiberglass.

What R-value insulation to use in an attic?

Ideally, you should have an R-38 value in your attic which is about 10 to 12 inches of insulation.

Can I use faced insulation in my attic?

Yes, you can use either faced or unfaced in your attic. Faced insulation provides a slight moisture barrier to protect the insulation. However, the faced insulation must have the plastic or paper facing out to create a moisture barrier.

How much does it cost to remove insulation from an attic?

It costs approximate$1,50-$2.00 per sq. ft. to remove insulation from an attic.

How much does it cost to have insulation blown into the attic?

An average-size attic of 1,200 square feet will usually cost about $1,700-$2,000 for blown-in cellulose or fiberglass.

How much does it cost to spray foam an attic?

Spray foam usually costs $3-$4 per square foot to install in an attic space.

What is the best type of insulation for an attic?

Cellulose or fiberglass blown-in insulation are both made from recycled materials and are ideal for use in an attic.

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Remodeling Terms Cheat Sheet

Definitions in laymen's terms, cost considerations, pictures and things you need to know.See full cheat sheet.

1Fiberglass: Plastic that is reinforced with glass fibers. The fibers may be mixed randomly throughout the plastic, or come in the form of a flat sheet, or be woven into a fabric

2Soffit: Construction material, typically composed of vinyl or aluminum, used to enclose the underside of eaves and ceilings

3Vapor barrier: A protective cover, commonly made of polyethylene, used for damp proofing walls and floors

4Drywall: (Also known as Sheetrock) Type of plasterboard, commonly used to build walls and ceilings, composed of gypsum that is layered between sheets of heavy paper

5Caulking: A chemical sealant used to fill in and seal gaps where two materials join, for example, the tub and tile, to create a watertight and airtight seal. The term "caulking" is also used to refer to the process of applying this type of sealant

How much does it cost to insulate an attic in my city?

Cost to insulate an attic varies greatly by region (and even by zip code). To get free estimates from local contractors, please indicate yours.